Valuation of amenity trees – Jon Heuch

In the second of a two-part series, arboricultural consultant Jon Heuch considers the past and the future of the monetary valuation of trees

In 2015 house prices and land values are ten times what they were in 1980, far outstripping the retail price index. So by 2006, the estimates produced by the Helliwell system appeared to be increasingly small and irrelevant. This led to new considerations of how best to estimate the value of amenity trees. Chris Neilan and others developed Capital Asset Value for Amenity Trees (CAVAT); others looked to the USA to see what the Council for Tree and Landscape Appraisers (CTLA) and i-Tree had on offer. This divergence of opinion has led to a confusing situation in 2015 with no guidance to arborists on what professional valuation practice looks like.

Valuation has also been downgraded from a Level 6 issue in the Professional Diploma in Arboriculture to a Level 4 issue. In comparison, in order to provide valuation services, a Chartered Surveyor needs first to qualify and then show the necessary experience to become a member of the Valuation Professional Group, which takes several years. At some time in 2015 the results of the i-Tree inventory of London trees will emerge. This will produce estimates of the value of the air quality improvements that vegetation might yield in terms of carbon and health. In addition a ‘structural value’ based on CAVAT will be produced. The structural value estimate will be immense as CAVAT produces large values. The potential for confusing structural and ecosystem service values is all too apparent.

An economics consultancy working for The Woodland Trust recently estimated the total value of UK woodland as £270bn. The apparently back of an envelope calculations use a value of £140,000 per hectare (ha) for lowland broadleaved woodland, assuming all 0.9m ha have the same unit value. Considering that smallish plots of broadleaved woodland in much of southern England can be bought in 2015 for around £10-15,000 per ha there appears to be a large gap between what private purchasers are prepared to pay and what theoretical economists believe public policy should assume.

High values are useful for those who want to influence public policy in favour of tree and woodland retention without having to depend on the real incomes that might arise from woodland management.

Higher values means greater importance for public officials and non-government conservation organisations. The trouble is, while some trees are important for a variety of reasons, many are not. Some trees are easily replaceable but some, if retained, cause annoyance, limit the potential for development or lead to unnecessary costs being incurred. Separating the important from the mundane is critical both for the industry’s credibility and to maximise the effectiveness of protecting the important. Detailed knowledgeable valuation might assist in doing this; generalised valuations based on the highest values do not.

While the Helliwell system still has the endorsement of the Arboricultural Association, the other systems have until recently been ignored by our professional bodies – the Arboricultural Association and the Institute of Chartered Foresters.

When it comes to public policy matters, poorly thought through valuations may just be ignored. When it comes to potentially adversarial situations that could end in court action where valuations may be crossexamined, there is potential for embarrassment and egg-on-face.

Above all, a valuation is statement of opinion, not fact. The weight given to that opinion in any adversarial situation should depend upon the experience of the person giving the valuation. There is a standard way of expressing that opinion whether it be in an Expert Witness Report (for the courts) or in a Proof of Evidence (for a planning appeal inquiry). If an estimate of monetary valuation is to be used as part of these documents they need the proper evidence base and awareness of assumptions in order to be used appropriately.

Jon Heuch is Principal Arboricultural Consultant at Duramen Consulting www.duramen.co.uk He will be leading the Valuation of Amenity Trees training course at Wyre Forest District Council 30 June to 1 July.